At the scene

For families living around the small community of Springwood in the Blue Mountains, many have had their lives turned upside down. Australians are well used to the threat of bush fires, but nothing can prepare you for the moment when you return home to find your house and everything inside utterly gutted by fire.

"It's devastating but we're all here and that's the main thing," Chris Muller told me, as her daughter picked through the smouldering rubble of her mother's home.

Among the few recognisable things are a couple of silver spoons and a battered coffee pot.

"We're looking for one of my cats Olly. We hope he managed to hide down the drain," she tells me.

Several fires are still burning around Springwood. Relays of helicopters whirr through the smoky haze, dumping water to try and douse the flames. A drop in the temperature today has given fire fighters a window to try and get on top of the situation before the weekend, when the mercury is expected to rise again. It's only spring here. The fear is of a long and difficult summer fire season.

Correspondents say bushfires are common in Australia but they have come earlier than normal this year, sparking concerns of further problems to come.

Minister for Police and Emergency Services Michael Gallacher told the BBC that "the speed and the ferocity" of the fires was something "not seen for many, many years".

"We had one fire front that changed direction and had a front to it, so if you can imagine, burning in one direction 25km [15 miles] wide."

"We're only now in the process of being able to return to some of the sites to check the magnitude of the losses and I've got to say, it's going to be quite substantial," he added.

Hundreds of residents spent Thursday night in evacuation centres, with many returning home to find their houses razed.

Fire fighters described blazes as tall as 20m to 30m (100ft).

A 63-year-old man died from a heart attack as he tried to defend his home in Lake Munmorah, in the Central Coast region of NSW, on Thursday afternoon.

Around 2,000 fire fighters across the state worked to try and contain the fires but many are still burning out of control, says the BBC's Jon Donnison.

Mr Abbott, in Winmalee, said of those helping to battle the fires: "These are ordinary people who, on an extraordinary day, come together to support their community and to protect their fellow Australians."

At least three fire fighters have been reported injured.

The NSW Rural Fire Service said an initial assessment of the Winmalee and Springwood areas showed that 81 properties had been destroyed, with 37 damaged.

"Approximately 30% of the fireground has been assessed," it said. "The number of properties destroyed or damaged will rise."

Reports estimate that as many as 200 homes could be lost in total.

The fires have been caused by unseasonably hot temperatures and strong winds. While these have now died down, more hot weather is forecast next week.

Ron Fuller, who lost his home in Winmalee, told ABC News: "We've had a number of fires through here before but this was an extraordinary fire. The speed was extraordinary, it just raced through this whole area, took out some houses, left other ones standing."

Jodie Harrison, Mayor of Lake Macquarie, said that four heritage homes, as well as a historic jetty, were caught in the fire.

"It's been confirmed that four houses in the heritage village of Catherine Hill Bay have been lost," she told local media.

Darkened skyline

NSW Premier Barry O'Farrell, in an interview on broadcaster 7 News, called the fires "some of the worst we have experienced around Sydney in living memory".

"We're in for a long, tough summer," he added.

Alex Chesser, a District Officer with the New South Wales Rural Fire Service, told the BBC that the fires had come unusually early.

"It's... a combination of a couple years of quite wet summers and winters which have allowed the bush to continue to grow at high rates, and also prevented us undertaking as many hazard reduction burns as we'd like," he said.

Smoke and ash from the wildfires blanketed the Sydney skyline on Thursday.

New South Wales was also hit by bush fires in September, which injured several fire fighters.